(a) Field of the Invention
This invention generally relates to pipe fabrication and more particularly to pipe fabrication from rolls of flat metal plate by alternately welding the pipe's longitudinal seam with a pair of arc welding machines.
(B) Description of the Prior Art
Most pipeline fabricating plants whether onshore or offshore use sections of finished pipe which are welded together. A considerable amount of research went into the development of very fast welding machines for welding the circular seams between such abutting pipe sections. The speed of such pipeline fabrication can be improved by using longer pipe sections. In practice, however, space limitations preclude the use of vary long pipe sections, as for example, on an offshore pipe-laying barge.
U.S. Pat. Nos. 3,251,332 describes an alternate method of pipeline fabrication from rolls of flat metal plate. However, no commercial pipe laying barge is believed to use this patented method which has considerable drawbacks, the most serious of which are that the success of this method depends on the ability of maintaining the pipe-laying barge on course, and the relatively low welding speed.
Applicant has overcome the drawbacks of the prior art, and provides a pipeline fabricating method, using rolls of flat metal plate. Applicant's pipeline fabricating plant is very fast, economical, and lends itself especially for use on an offshore vessel.